What is a side return extension?
A side return extension fills the narrow passage that runs alongside the back addition of many Victorian and Edwardian terraced houses. It widens a galley kitchen into a proper kitchen-diner, usually with a sloping glazed roof to keep the room bright.
How much does a side return extension cost in Lancing?
In Lancing, a side return extension typically costs £2,600–£3,700 per m² of floor area, including VAT at 20% (standard rate). For a typical 12 m² project that is roughly £31,000–£44,500. Building costs in the South East run about 12% above the UK average, and the figures for Lancing are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (8 m²) | £21,000–£29,500 |
| Typical project (12 m²) | £31,000–£44,500 |
| Larger project (17 m²) | £44,000–£63,000 |
| Rate per m² | £2,600–£3,700 |
What moves the price most:
- Party wall surveyor fees
- Steel beams and propping of the back addition
- Length of the side return
- Access through the house for materials
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a side return extension in Lancing?
Approvals for a side return extension in Lancing follow the rules for England. In England a side return infill is treated as a side extension. It may be permitted development if it is single-storey, no more than 4 metres high and no wider than half the original house, but not in a conservation area. Because side returns sit on the boundary, party wall notices are almost always needed.
Building regulations approval comes from the council’s building control service or a registered building control approver. The work is inspected at key stages, such as foundations, drainage and insulation, and a completion certificate is issued at the end.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
On a typical side return extension we handle:
- Party wall advice and notices
- Foundations and drainage, including any build-over agreement
- Glazed or solid roof with insulation
- Building control sign-off
- Drawings and planning or permitted development check
- Floor levelling, heating and electrics
How long does it take?
Build time is typically 10 to 14 weeks on site. Design and approvals come first and typically take 3 to 4 months, depending on the approval route.
Building in Lancing
Commuter towns across the South East have many 1930s and post-war semis that suit rear extensions and hip-to-gable loft conversions.
From BN99 outwards, we take on projects throughout Lancing and the surrounding parts of West Sussex.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about side return extensions in Lancing
Is a glass roof too hot or cold?
Modern solar-control double or triple glazing reduces glare and heat loss. Building regulations also limit how much glazing you can have unless the design shows it performs well enough.
Who approves a side return extension in Lancing?
Planning matters in Lancing go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
How much space does a side return add?
Typically 1.5 to 2.5 metres of width along the back addition. It often turns a narrow galley kitchen into a family kitchen-diner.
Will I need a party wall agreement?
Almost certainly in England and Wales, because side returns sit on or near the boundary. Notices must be served before work starts, and a party wall surveyor may be appointed if the neighbour does not consent.
How much does a side return extension cost in Lancing?
In Lancing, a side return extension typically costs £2,600–£3,700 per m² of floor area, including VAT at 20% (standard rate). A typical 12 m² project comes to roughly £31,000–£44,500. Your fixed price depends on the survey and drawings.